When the penis misses the vagina completely and goes full force into the taint. The resulting force causes a severe bend or flex in the erect penis resulting in pain and discomfort to the penis and sometimes the taint region.

I was bangin your mom super hard from behind, she was really liking it. She started bucking around and I tried to slam it in there hard and got a severe sploink that pretty much put me out of commission for an hour or so.